The RS-84 was the Boeing Rocketdyne Lox/Kerosene design for NASA's Space Launch Initiative. The design borrowed extensively from Russian technology developed in the forty years since the USA began its last such design, the F-1. The engine featured a high-pressure chamber and staged combustion cycle in comparison with the F-1's lower pressure chamber and gas generator. Another requirement was to produce the first US reusable Lox/Kerosene engine. This made it necessary to limit the kerosene temperature while cooling the thrust chamber, and limit soot build-up in the turbine. To accomplish this the RS-84 included an arrangement of small section manifolds along the combustion chamber and engine nozzle. These manifolds were spaced so the kerosene was not heated above the coking limit. Some manifolds also injected a small amount of kerosene directly into the thrust chamber to create film wall cooling. The oxygen-rich staged combustion used a cleaner, heated oxygen gas to drive the turbine to avoid problems inherent in kerosene-rich gas products. On 19 March 2004 NASA announced cancellation of further development of the RS-84.

Objectives of the RS-84 were improved safety (33 failures per million missions), reduced costs ($ 1 million-per-use life cycle cost) and improved operability (10-shift turn time). An oxygen-rich combustion cycle using RP-1 kerosene fuel had been selected by SLI Architectures as the best cycle, due its inherent safety and operability features, and excellent performance and packaging. Objectives of the program were design and test of 1 million pound thrust prototype engine, validation of existing and new analytical tools, and to provide the groundwork for a decision to proceed with full-scale development.

Figures given here are for the ultimate production engine design. The prototype engine would have 4732 kN at sea level; 5026 kN in vacuum; an 8-shift turn time; a specific impulse of 305 at sea level and 324 in vacuum; a dry weight of 8128 kg; a life of 100 missions; and a 20:1 area ratio, length of 3.73 m, diameter of 2.74 m.

Lox/Kerosene Liquid oxygen was the earliest, cheapest, safest, and eventually the preferred oxidiser for large space launchers. Its main drawback is that it is moderately cryogenic, and therefore not suitable for military uses where storage of the fuelled missile and quick launch are required. In January 1953 Rocketdyne commenced the REAP program to develop a number of improvements to the engines being developed for the Navaho and Atlas missiles. Among these was development of a special grade of kerosene suitable for rocket engines. Prior to that any number of rocket propellants derived from petroleum had been used. Goddard had begun with gasoline, and there were experimental engines powered by kerosene, diesel oil, paint thinner, or jet fuel kerosene JP-4 or JP-5. The wide variance in physical properties among fuels of the same class led to the identification of narrow-range petroleum fractions, embodied in 1954 in the standard US kerosene rocket fuel RP-1, covered by Military Specification MIL-R-25576. In Russia, similar specifications were developed for kerosene under the specifications T-1 and RG-1. The Russians also developed a compound of unknown formulation in the 1980's known as 'Sintin', or synthetic kerosene. More...

Bibliography

Mansfield, Simon, editor, Space Daily, The best source for space news on the web.. Web Address when accessed: here.